hello everyone,
i'm a complete beginner on arduino, and I was trying to make a clock with 4 single digit 7 segment display with common anode with, a tiny RTC module and a 74HC595. I did it like this:
After coding several hours all I can get is 4 "zero" displayed on the 7 segments displays and the 2 LEDs correctly flicking. Here is my code:
// Date and time functions using a DS1307 RTC connected via I2C and Wire lib
#include <Wire.h>
#include <RTClib.h>
// set shift register pins
#define data_pin 13
#define latch_pin 12
#define clock_pin 11
// set digit segments 5V pins
#define d1_pin 1
#define d2_pin 2
#define d3_pin 3
#define d4_pin 4
#define dot_pin 7
#define rotation_cycles 6 // set number of rotation cycles per digit in 'rotation' effect mode
#define mux_delay 3 // set delay between switching display of digits
#define num_digits 10
// define digits, 0 - on, 1 - off
byte segments[10] = {
0b00000001, // 0
0b01100111, // 1
0b00010010, // 2
0b01000010, // 3
0b01100100, // 4
0b01001000, // 5
0b00001000, // 6
0b01100011, // 7
0b00000000, // 8
0b01000000 // 9
};
byte segments_off = 0b01111111;
// set variables that will keep previous values for minutes and hours to be compared with current values at next run
int prev_minutes = 0;
int prev_hours = 0;
int max_cycles = rotation_cycles * num_digits - 1;
int cycles_remaining = max_cycles; // variable to count remaining cycles for 'rotation' effect
int mod_digit = 0; // digit to be modified during 'rotation'
boolean hide_first_hour = false; // tell the display function whether to show or hide leading zero for hours
boolean first_run = true;
// variables indicating which digit changed
boolean m1_change = false;
boolean h2_change = false;
boolean h1_change = false;
// create RTC object for clock
RTC_DS1307 RTC;
// HELPER FUNCTIONS
// clears digits on display by turning power off
void clearDisplay() {
digitalWrite(d1_pin, LOW);
digitalWrite(d2_pin, LOW);
digitalWrite(d3_pin, LOW);
digitalWrite(d4_pin, LOW);
}
// display single digit
void displayDigit(int digit_pin, int number) {
// using shift register to light up required led segments
digitalWrite(latch_pin, LOW);
shiftOut(data_pin, clock_pin, LSBFIRST, segments[number]);
digitalWrite(latch_pin, HIGH);
// blank display
clearDisplay();
// light up required digit
digitalWrite(digit_pin, HIGH);
}
// display time
void displayTime(int hours, int minutes) {
int h1, h2, m1, m2;
h2 = hours % 10;
h1 = ((hours % 100) - h1) / 10;
m2 = minutes % 10;
m1 = ((minutes % 100) - m1) / 10;
if (hide_first_hour == true) {
clearDisplay(); // diplay first hour digit only if it is greater than 0
}
else
{
displayDigit(d1_pin, h1);
}
delay(mux_delay);
displayDigit(d2_pin, h2);
delay(mux_delay);
displayDigit(d3_pin, m1);
delay(mux_delay);
displayDigit(d4_pin, m2);
delay(mux_delay);
}
// blink dot
void blinkDot(int seconds) {
if ( (seconds % 2) == 0 ) {
clearDisplay();
digitalWrite(latch_pin, LOW);
shiftOut(data_pin, clock_pin, LSBFIRST, segments_off);
digitalWrite(latch_pin, HIGH);
digitalWrite(d2_pin, HIGH);
digitalWrite(dot_pin, LOW);
} else {
clearDisplay();
digitalWrite(dot_pin, HIGH);
}
delay(mux_delay);
}
// modify single digit for 'rotation' effect
int modifyDigit(int digit) {
// int cycle = (cycles_remaining - (cycles_remaining % num_digits)) / rotation_cycles;
int cycle = cycles_remaining / rotation_cycles;
digit += (num_digits-cycle-1);
digit %= 10;
return digit;
}
// modify time for 'rotation' effect
void modifyTime(int *time2display) {
int h2 = time2display[0] % 10;
int h1 = int(time2display[0] / 10);
int m2 = time2display[1] % 10;
int m1 = int(time2display[1] / 10);
// modify digit whose turn it is as determined by mod_digit
switch (mod_digit) {
case 4:
m2 = modifyDigit(m2);
break;
case 3:
m1_change = false;
m1 = modifyDigit(m1);
break;
case 2:
h2_change = false;
h2 = modifyDigit(h2);
break;
case 1:
h1_change = false;
h1 = modifyDigit(h1);
break;
default:
break;
}
// keep higher digits from changing while lower digits 'rotate' by reducing them by one
if (mod_digit != 0) {
if (m1_change == true) {
m1 = (m1 + 10 - 1) % 10; // add ten before reducing by one to avoid going negative, then get remainder to avoid number higher than ten
m1 = min(m1, 5); // higher minute digit cannot be greater than 5
}
if (h2_change == true) {
h2 = (h2 + 10 - 1) % 10;
// set h2 to 2 instead of 9 at midnight
if (h1_change && h1==0) {
h2 = min(h2, 2);
}
}
if (h1_change == true) {
h1 = (h1 + 10 - 1) % 10;
h1 = min(h1, 2); // higher hour digit cannot be greater than 2
}
}
m2 %= 10;
m1 %= 10;
h2 %= 10;
h1 %= 10;
// modify time array directly as it was passed to this function by reference - nothing to return
time2display[0] = h1*10 + h2;
time2display[1] = m1*10 + m2;
}
// MAIN PROGRAM BODY
void setup() {
// set pin modes
pinMode(data_pin, OUTPUT);
pinMode(latch_pin, OUTPUT);
pinMode(clock_pin, OUTPUT);
pinMode(d1_pin, OUTPUT);
pinMode(d2_pin, OUTPUT);
pinMode(d3_pin, OUTPUT);
pinMode(d4_pin, OUTPUT);
pinMode(dot_pin, OUTPUT);
// start connection with clock and the clock itself
Wire.begin();
RTC.begin();
// set the clock to current system time - uncomment when need to set time then comment again
RTC.adjust(DateTime(__DATE__, __TIME__));
}
void loop() {
// read time
DateTime now = RTC.now();
int hours = now.hour();
int minutes = now.minute();
int seconds = now.second();
int days = now.day();
int months = now.month();
int hours2display, minutes2display;
// check if any of time digits (except lower minutes) changed and if yes mark them as subjected to correction during 'rotation'
if ( ( int(minutes/10) != int(prev_minutes)/10 ) && !first_run ) {
m1_change = true;
}
if ( ( (hours % 10) != (prev_hours % 10) ) && !first_run ) {
h2_change = true;
}
if ( ( int(hours/10) != int(prev_hours)/10 ) && !first_run ) {
h1_change = true;
}
// determine whether to hide or display leading hour digit
if (hours < 10) {
hide_first_hour = true;
}
else if (hours == 10 && h1_change == true) {
hide_first_hour = true;
}
else
{
hide_first_hour = false;
}
// display time
displayTime(hours2display, minutes2display);
blinkDot(seconds); // blink divider dot
}
I was thinking that this was due to a problem on the RTC, but when I deplug it, LEDs stop flicking, so I assume that this part of code is right, but I really don't understand why it dosen't show anything else than 4 zeros.
I really tried everything I could, but I have no solution, that's why i'm posting here today 
Anyone got any advice?
Cheers!
Alex
P.S. This is the tiny RTC module i have. Do I have to place a PNP component on it ?
Thanks for answer.
